limenuke

I posted a week ago about brake issues. Everyone basically said:
- your fluid isn't great (I fleshly bleeded via both gravity and vacuum)
- you havent tapped your brake calipers (I did)
- you need to torque your lines correctly (I did)
- your brake pads aren't good (this is unlikely the issue)
- your tires are too grippy for your brakes to lockup easily

As it stands, w/ engine on, I can press the brake pedal about 50% of the way with little effort (seems like mostly free play), before pedal gets pretty firm. In the remaining 50% of travel, I get good modulation. I can press the pedal to the floor with quite a bit of effort, and it's enough to trigger ABS (locking up front wheels). However, I can definitely feel the brake pedal hitting the stopper at the end of the travel when I'm doing this.

Based on my experience with other cars (I can trigger ABS without hitting the brake stopper, on stock shitty pads), I feel that my s2k's brakes are underperforming...so the only thing left to do is:

1) Try other people's s2ks and see if their brakes are better.
2) replace/bench bleed my brake master cylinder.

I guess I'll go with option 1) this week.
I feel like my BMC isn't busted because when I have the car's engine off, I can pump the brakes once or twice and the pedal becomes rock hard. With constant pressure, the pedal does not sink at all which makes me feel like the seals are still good.

Has anyone experienced a significantly better pedal travel from bleeding their master cyl?

nubbel

I am also trying to improve my brake feel, but haven't had the time to do another full bleed yet, however, I am not hitting the stopper like you mentioned.

Billman's brake-pedal-hold-down-over-night-trick seems to have some positive impact but to be sure I want to do it once more and then do a full bleed afterwards.

Please post your findings!

twohoos

Air in the ABS module. Find a safe place to engage ABS for a solid 1-2 sec continuously. Pedal feel should improve immediately. (Note, short ABS engagements won't work, no matter how many times you repeat it. It must be a good, long hard stop.)

limenuke

I just bled my master cylinder and found that if I make fast pedal strokes, I introduce microbubbles into my fluid (from the hose going into the reservoir)
If I do slow strokes, no bubbles appear.

I must have done 200 different speed strokes while bleeding to observe this. I don't know where the bubbles could be coming from. I have the hose from the ABS line going into the fluid and I've made sure the end of the hose is submerged.


@twonoos
Thanks for the advice. I will do this. If this "clears" the lines, where do the air bubbles go? Do I just have to do a normal bleed?

B serious

The theory behind the ABS engagement technique is that the bubbles "shake" loose from all the little cavities in the ABS unit and rise to the uppermost portion of the system - the MC reservoir. So no...you wouldn't need a brake bleed after.

Unfortunately, this method doesn't work every time.

VashTheStampede

How do the brake hose connectors at the calipers look? The metal "skirt" that crimps down onto the rubber hose has been known to fail on S2000s with, unfortunately, fatal results. Check all corners for any signs of leaks, even very minor ones. Again, that's just upstream from the calipers, where the metal portion of the brake like meets the rubber. You may have a micro-crack in one of those locations. It goes without saying that any sort of driving with that kind of issue present can kill you.

shind3

I think this may have been the 2nd time I've seen this mentioned on this forum. Your was also probably the 1st.

I wonder if it's worth trying to rig something like two small motors (or two buddies that will sit there spinning the front rotors) with the calipers off. Then, insert a piece of wood between the pads so you can hit the brakes with the engine on (in gear) and have it vibrate the hell out of the ABS pump for a good long time in a safe/controlled environment. It might be easier to try this on the rear first and see if that is good enough since that would be a 1 person job. Though, I wonder if the car wants to see the same wheel speeds front and rear for a while so its ABS self-test that it does on every startup will pass.

Anyone wanna give this a shot?

Kazuken

Will this article help? Robinette's guide to bleeding the master cylinder. I have never done this before, but have seen this mentioned a few times.
https://robrobinette.com/bleeding_th...r_cylinder.htm

B serious

^bleeding the module in a less insane, more foolproof way as described here is a better idea.

Car Analogy

I mean, maybe start with that. But I think we're all secretly hoping for the wood brake pad bleed YouTube video...